Hey, are you saying that somehow they have a physical link between each other, or that there is an isp that is connecting them?
Hi @jallen314 ,
A backdoor is usually a physical link connecting two sites. On this link, we run an IGP. This link could be owned by an enterprise, or perhaps an ISP provides it.
Rene
I see. Just for the sake of failover then why prioritize the OSPF here we already know the limitations of IGPs why use it for external networks
Hello Sambhaji
The use of a BGP backdoor is not something that should be used often nor should it be applied as a best practice. It should only be used out of necessity, and with great care, to resolve issues of redundancy or as temporary measures during a merger or a network migration.
You are right that IGPs have limitations as far as routing on the Internet is concerned, and as far as extremely large networks go. BGP backdoors shouldn’t typically be applied on the Internet. They should only be applied within an enterprise network. In the lesson, the example described that AS1 and AS 2 belong to the same enterprise. These locations will typically be in the same building, in the same campus, or they may be remote but have an independent backup path between them. Only under such circumstances would you use this feature.
While BGP backdoor routes can offer benefits, they also require careful planning and management to avoid unintended routing behaviors or conflicts with existing routing policies. The decision to use a backdoor route should consider the specific needs and architecture of the network, as well as the potential impact on traffic patterns and network performance.
I hope this has been helpful!
Laz